如何在函数内的另一个类中放置一个警告对话框

时间：2015-09-23 06:16:31

标签： android alertdialog

我已经在我的应用中创建了自定义date and time picker，现在我已多次使用picker。因此，为了避免代码的冗余，我认为我应该将该函数放在另一个类的单独函数中，我可以在每次需要时调用它，但我无法这样做，请帮助。 单独的类是：

public class DateTimePicker {
    String str;

    public String returnDate(final Context ctx) {
        AlertDialog.Builder builder1 = new AlertDialog.Builder(ctx);
        final DatePicker picker1 = new DatePicker(ctx);

        try {
            Field f[] = picker1.getClass().getDeclaredFields();
            for (Field field : f) {
                if (field.getName().equals("mYearPicker")|| field.getName().equals("mYearSpinner") ) {
                    field.setAccessible(true);
                    Object yearPicker = new Object();
                    yearPicker = field.get(picker1);
                    ((View) yearPicker).setVisibility(View.GONE);
                }
            }
        } catch(Exception ex) {
            ex.printStackTrace();
        }
        picker1.setCalendarViewShown(false);

        builder1.setTitle("Please select date on which you would be leaving :")
            .setView(picker1)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    SimpleDateFormat parseFormat = new SimpleDateFormat("EEE dd MMM");
                    Date date1 = new Date();
                    date1.setDate(picker1.getDayOfMonth());
                    date1.setMonth(picker1.getMonth());
                    final String s = parseFormat.format(date1);
                    Log.e("DATE",s);

                    //Time picker
                    AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
                    final TimePicker picker = new TimePicker(ctx);
                    picker.setIs24HourView(true);
                    builder.setTitle("Please select time at which you would be leaving :")
                        .setView(picker)
                        .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int whichButton) {
                                int hour = picker.getCurrentHour();
                                int minute = picker.getCurrentMinute();
                                str = s + " " + hour + ":" + minute;
                            }
                        })
                        .setNegativeButton("One way", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int whichButton) {
                                dialog.dismiss();
                            }
                        }).create().show();
                        //Time picker
                    }
                }
            )
            .setNegativeButton("One way", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    dialog.dismiss();
                }
            })
            .create().show();

        return "hello "+ str ;
    }

以及我使用上述类的代码是：

DateTimePicker obj = new DateTimePicker();
Log.e("Object", "Created");
String st = obj.returnDate(this.getActivity());
Log.e("Function", "Called");
System.out.println("Value returned :" + st);
leaving.setText(st);

在日志中我得到＆＃34; hello null ＆＃34;一旦我调用了它甚至不等待用户输入的功能，evething就会被打印出来。 请帮忙谢谢

5 个答案:

答案 0 :(得分：0)

如果您调用show（），代码将不会停止并等待用户输入。尝试添加：

[...]
}).create().show();
Log.i("Dialog", "Show called");

了解会发生什么。

如果你想使用Dialog中的输入数据，你必须从正面按钮监听器中调用一个函数：

.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {
        int hour=picker.getCurrentHour();
        int minute=picker.getCurrentMinute();

        sendToSomewhere("+hour+":"+minute");
    }
})

答案 1 :(得分：0)

您将始终返回“hello null”，因为该对话框在内部创建了一个新线程，并且该对话框的答案仅在相应的按钮单击侦听器中可用。

您可以做的是为创建对话框的函数提供callback方法，并在对话框中得到答案后调用此方法。

有关如何将函数作为参数传递的详细信息，请参阅Java Pass Method as Parameter。

修改

第二个想法是，将onClickListeners作为对话函数的参数发送会更优雅。

您可以为流程中的所有三个最后一个按钮定义onclick，如

DialogInterface.OnClickListener
     yesButton = new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                    int hour = picker.getCurrentHour();
                    int minute = picker.getCurrentMinute();
                    str = s + " " + hour + ":" + minute;
                     SomeFunction();
            }
        });

将这些对象中的3个传递给对话框函数，而不需要像

这样的函数头 
public void returnDate(final Context ctx, OnClickListener yes, OnClickListener no1, OnClickListener no2) {

答案 2 :(得分：0)

基本上你应该定义返回void的方法。要接受用户输入String，您可以使用回调。

  • 获取OnUserInputListener作为构造函数的句子（尽管你可以通过其他方式获取它）
  • 在DateTimePicker类中定义界面。

您的DateTimePicker课程如下：

public class DateTimePicker {
    private final OnUserInputListener onUserInputListener;

    // String str; <-- this field value has no use

    DateTimePicker(OnUserInputListener onUserInputListener) {
        this.onUserInputListener = onUserInputListener;
    }

    public void returnDate(final Context ctx) {

        ...

        public void onClick(DialogInterface dialog, int whichButton) {
            int hour = picker.getCurrentHour();
            int minute = picker.getCurrentMinute();
            str = s + " " + hour + ":" + minute;
            onUserInputListener.onUserInput(str); // CALL BACK!!!
        }

        ...

    }

    public interface OnUserInputListener {
        void onUserInput(String string);
    }
}

对于调用者类，它应该实现OnUserInputListener。

public class MainActivity extends Activity implements OnUserInputListener {

    ...

    DateTimePicker obj = new DateTimePicker(this);
    obj.returnDate(this.getActivity());

    ...

    @override
    public void onUserInput(String string) {
        System.out.println("Value returned :" + string);
        leaving.setText(string);
    }
}

答案 3 :(得分：0)

这可能会对你有帮助！

public class DatePickerFragment extends DialogFragment implements
        DatePickerDialog.OnDateSetListener {
    TextView textView, tv;

    public DatePickerFragment(TextView textView, TextView text) {
        this.textView = textView;
        tv = text;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Use the current date as the default date in the picker
        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);
        return new DatePickerDialog(getActivity(), this, year, month, day);
    }

    public void onDateSet(DatePicker view, int year, int month, int day) {
        mCalendar.set(Calendar.YEAR, year);
        mCalendar.set(Calendar.MONTH, month);
        mCalendar.set(Calendar.DAY_OF_MONTH, day);
        SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);
        String dateForButton = dateFormat.format(mCalendar.getTime());
        textView.setText(dateForButton);
        tv.setVisibility(View.VISIBLE);
    }
}

和show dialog 

dateFragment = new DatePickerFragment(toDate, tvTo);
dateFragment.show(getFragmentManager(), "Dialog Title");

您可以在活动/自定义类

中使用它

答案 4 :(得分：0)

尝试在DateTimePicker中添加自定义日期选择的侦听器：

public interface OnDateSelectedListener{
  public void onDateSelected(String date);
}

在DateTimePicker中添加自定义接口并设置侦听器引用returnDate：

public class DateTimePicker {

    public void returnDate(final Context ctx, final OnDateSelectedListener onDateSelectedListener) {
        AlertDialog.Builder builder1 = new AlertDialog.Builder(ctx);
        final DatePicker picker1 = new DatePicker(ctx);

        try {
            Field f[] = picker1.getClass().getDeclaredFields();
            for (Field field : f) {
                if (field.getName().equals("mYearPicker") || field.getName().equals("mYearSpinner")) {
                    field.setAccessible(true);
                    Object yearPicker = new Object();
                    yearPicker = field.get(picker1);
                    ((View) yearPicker).setVisibility(View.GONE);
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        picker1.setCalendarViewShown(false);

        builder1.setTitle("Please select date on which you would be leaving :")
                .setView(picker1)
                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int whichButton) {
                                SimpleDateFormat parseFormat = new SimpleDateFormat("EEE dd MMM");
                                Date date1 = new Date();
                                date1.setDate(picker1.getDayOfMonth());
                                date1.setMonth(picker1.getMonth());
                                final String s = parseFormat.format(date1);
                                Log.e("DATE", s);

                                //Time picker
                                AlertDialog.Builder builder = new AlertDialog.Builder(ctx);
                                final TimePicker picker = new TimePicker(ctx);
                                picker.setIs24HourView(true);
                                builder.setTitle("Please select time at which you would be leaving :")
                                        .setView(picker)
                                        .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                                            public void onClick(DialogInterface dialog, int whichButton) {
                                                int hour = picker.getCurrentHour();
                                                int minute = picker.getCurrentMinute();
                                                onDateSelectedListener.onDateSelected(s + " " + hour + ":" + minute);
                                            }
                                        })
                                        .setNegativeButton("One way", new DialogInterface.OnClickListener() {
                                            public void onClick(DialogInterface dialog, int whichButton) {
                                                dialog.dismiss();
                                            }
                                        }).create().show();
                            }
                        }
                )
                .setNegativeButton("One way", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                        dialog.dismiss();
                    }
                })
                .create().show();
    }

    public interface OnDateSelectedListener{
        public void onDateSelected(String date);
    }

}

现在使用OnDateSelectedListener引用调用DateTimePicker：

DateTimePicker dateTimePicker = new DateTimePicker();
dateTimePicker.returnDate(this.getActivity(), new DateTimePicker.OnDateSelectedListener() {
   @Override
   public void onDateSelected(String date) {
      leaving.setText(st);
   }
});
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